Technical Field
Embodiments of the present invention generally relate to a developing device, a process cartridge, and an image forming apparatus, such as a copier, a printer, a facsimile machine, or a multifunction peripheral having at least two of copying, printing, facsimile transmission, plotting, and scanning capabilities.
Description of the Related Art
Electrophotographic image forming apparatuses, such as copiers and printers, form visible images with developer on an image bearer, such as a photoconductor and an intermediate transfer member, and transfer the images onto sheets of recording media. A certain amount of developer remains untransferred on image bearer and collected by a cleaning device. There are image forming apparatuses configured to return the developer collected by the cleaning device through a collected-developer passage to a developing device.
Although use of developer having lower melting point is promoted to reduce impact on environment, it is possible that such developer solidifies or adheres inside the developing device or the collected-developer passage (e.g., a collected-developer tube) due to temperature rise at the start of the apparatus and degradation of developer over time. When the apparatus is left unused under hot and humid conditions, the possibility of adhesion of developer also arises. When an impact such as vibration is given to the solidified developer in the collected-developer passage, there is a risk that the developer falls and is transported to the developing device, causing image failure.